In the electrophotography, a method which uses a heat roller has been widely employed in order to fix electrostatic latent images which are visualized by a toner. In this method, there has been a desire for a toner having excellent low-temperature fixability (that is, the toner has a low minimum fixing temperature) and a wide fixing temperature range.
If offset is caused on the heat roller, the fixing temperature range is referred to as the difference (T0-TL) between hot offset temperature (T0) and the minimum fixing temperature (TL). Generally, if a polymer having a low molecular weight is used as a binder resin, minimum fixing temperature decreases but hot offset temperature decreases; moreover, heat-resistant shelf stability lowers. On the other hand, if a polymer having a high molecular weight is used as a binder resin, hot offset temperature increases and heat-resistant shelf stability is improved; however, there is a problem that minimum fixing temperature increases.
There has been known a technique intended to solve the issue caused by the fact that the relationship between hot offset temperature and heat-resistant shelf stability and minimum fixing temperature is traded-off.
For example, Patent Literature 1 discloses a toner for developing electrostatic images comprising at least a binder resin, a charge control agent and a wax component, wherein a DSC curve of the wax has a predetermined endothermic peak and a half-value width, the wax component attributed to the predetermined endothermic peak of the wax is a predetermined ester wax, and a weight average particle diameter of the toner is in a predetermined range.
Patent Literature 2 discloses a toner for developing electrostatic images comprising a toner particle containing a binder resin formed by a styrene polymer or a styrene copolymer, a colorant, a polar resin and a predetermined solid wax.
Patent Literature 3 discloses a wax for a toner contained in a toner for electrophotography, comprising a first carboxylic acid ester compound having 32 to 41 carbons, a second carboxylic acid ester compound having 42 to 46 carbons and a third carboxylic acid ester compound having 47 to 62 carbons in a predetermined ratio.